Internal spa filter

ABSTRACT

An internal spa filter for a spa, having a filter body with an inlet opening at its one end and a discharge orifice at its opposite end, the sides of such body are formed with auxiliary spa water inlet openings. The filter also includes a filter bag having a sheath encompassing the exterior of the filter body and a pocket extending inwardly from the front end of the sheath into the filter body from the main spa water inlet opening. Operation of the spa water circulation system draws spa water into the main spa water inlet opening through the filter bag pocket into the filter body while concurrently spa water is drawn transversely through the filter bag sheath and auxiliary spa water openings into the filter body, all of such spa water flows rearwardly out of the filter body through the filter body discharge orifice.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to filters for liquids. More particularly,the present invention is directed to an internal filter for use in thewater circulation systems of conventional pools or spas.

2. Description of the Prior Art

Filters of various configurations are known in the art for use inswimming pools, spas, and the like in order to remove solid particlesand debris from the circulated water. Such filters are typically mountedin-line within the pool or spa circulation system and are configuredwith a liquid-permeable filter media such that when the circulationsystem is in operation, the water can be pulled through the filter andpumped back into the pool or spa, leaving the captured debris on thefilter for subsequent removal.

The conventional cartridge filter as is known and used in the art isgenerally comprised of a cylindrical filter element having one or morelayers or sheets of a porous material configured with a pore size toallow the passage of water while trapping and removing the solidparticles from the water that are unable to pass through the pores. Asthe filter traps more and more solid particles, the pores in the filtermedia become clogged, inhibiting the flow of water through the pool orspa's circulation system and thereby decreasing performance and possiblyeven damaging the circulation pump. In an attempt to address theseconcerns, the cartridge filters known in the art typically employrelatively large sheets of the porous filter material that are pleatedso as to provide an increased filter surface area, thus increasing thelife and performance of the filter, while not increasing the filter'soverall size. The filter material is maintained in its cylindrical,pleated configuration by being mounted on a rigid cylindrical core andcapped on each end by an annular end cap.

Though the conventional cartridge filter is in wide use, there are stillseveral shortcomings with this filter type that have not yet beenovercome. First, the flow rate through the cartridge filter is limitedby the material and configuration of the pleats and the apertures in therigid cylindrical core. Such flow rate is typically on the order of 100gpm when the filter is new. Second, despite the overall increasedsurface area of the filter material achieved by the pleats, only so muchof this surface area is truly usable, as the folds of the pleat aretight and are butted up against the cylindrical core. Moreover, asparticles and debris become lodged between the pleats, the useful filtersurface area that is lost is effectively doubled because the particlesand debris clog pores on both adjacent surfaces of the pleat. Thus,cartridge filters become clogged and experience decreased flow ratesrelatively quickly. A third shortcoming of the cartridge filters knownand used in the art is that they cannot be readily cleaned afterbecoming clogged. In the interest of increasing the total filter surfacearea, the pleats of the typical cartridge filter are numerous anddensely configured about the filter's circumference. Thus, in order toremove the debris trapped deep within the pleat folds, high pressurereverse flow or meticulous debris removal using a vacuum or manualtechnique between each pleat is necessary. It is further recommendedthat the cartridge be soaked overnight in a cartridge cleaning solutionand then be thoroughly cleaned a second time before being returned touse. Because of these inconveniences, some pool and spa owners simplyuse their cartridge filters until they become clogged and discard them,often prematurely, rather than bothering to clean them out. Moreover,because cartridge filters trap debris on the outside of the filter only,when the filter is removed from the pool or spa for cleaning ordisposal, it is possible that the debris that is loose and easilyremoved will fall off the filter into the clean side of the circulationsystem rather than being permanently removed.

For these reasons, other pool and spa filters have been proposed in theart. Diatomaceous earth (“DE”) filters house internal, parallel gridsmade of extremely fine mesh that is coated with DE, which is crushed,petrified bone that acts as an adhesive and traps particles and debrisfrom the water as it is filtered through the layers of DE grids. TheseDE filters are relatively more expensive than comparable cartridgefilters and may be subject to municipal or environmental authorityregulations pertaining to cleaning and disposal. Similarly, sand filtershave also been proposed that essentially use a sand and gravel filtermedium that mixes with the circulated water as it passes through thefilter to pull out dirt and debris. However, the debris is notpermanently captured by the sand filter medium and can eventually workits way through the filter and back into the pool or spa circulationsystem. It has been proposed that an additional solution be added to thesand to coagulate the particles and debris being filtered into largerclumps that can be more easily trapped by the sand filter medium. As afurther maintenance step with sand filters, periodically, the sanditself is depleted from the filter and more sand of a specific type mustbe added. Sand filters, like the DE filters, are more costly thancartridge filters.

Bag-type filters for separation of unwanted solids from liquid processflows have also been employed in various industrial filtrationapplications in the interest of increasing flow rate and efficiency. Tothis end, filter assemblies having bag filters supported on rigidstructures or stiffening frames and having elaborate sealingarrangements between the filter and the surrounding housing have beenproposed. For example, U.S. Pat. No. 4,769,052 to Kowalski is directedto a flexible fabric filter bag apparatus having multiple supportsurfaces. A double-walled, porous cylinder cooperates with a stretchingframe to suspend and support the filter bag within a rigid cylindricalouter housing. An annular flange is provided in the housing's inner walland is configured to sealingly engage a metal ring within the bag's openend when the bag, the double-walled cylinder, and the stretching frameare positioned inside the outer housing. A cover is installed over theopen end of the outer housing to seal the filter and to force thestretching frame downwardly to draw the filter bag taut against thesurfaces of the double-walled support cylinder.

U.S. Pat. No. 5,910,247 to Outterside is directed to a similar filterbag system. Like the Kowalski filter apparatus, Outterside disclosesessentially a double-walled filter support cylinder, consisting of anouter basket and an inner tubular member, a housing having a lid forsealing the filter, and a filter bag having a ring in its open end tosealingly engage a flange on the basket. Outterside further disclosesspecific dimensions for the filter bag which purportedly maximize thesurface area without restricting the process flow rate. Moreover, theOutterside system's supporting structures are configured to preventcollapse of the filter bag when the process flow is reversed to backwashand clean the filter without removing it. Hence, it is essential thatthe filter bag fit snugly and securely over the outer basket and innertubular member. To this end, Outterside discloses that the filter bodyis smaller in diameter than the outside diameter of the tubular supportmember so that the filter must be stretched to fit over the tubular bodyand is retained thereon through a frictional fit.

Therefore, the bag filters known and used in the prior art essentiallyentail a multi-walled support structure that may further includeadditional stretching or stiffening frames, a filter bag that is securedon the support structure and shaped by the alternative frames, and afilter housing, or vessel, that contains the filter bag assembly andprovides for a positive seal between the “dirty” and “clean” side of thefilter along a ring integral to the bag's open end. Based on theconfiguration and number of components in these prior art industrialbag-type filters, it follows that such filters are not well-suited foruse in spas because of their complex design and inherent relatively highcost. Furthermore, the housing, which plays a critical role in thefunction and performance of the prior art bag-type filters, isparticularly ill-suited for use in a spa's circulation system becausethe conventional spa's filter-receiving cavity cannot accommodate thehousing, and the housing itself, having only one small inletstrategically positioned above the location where the filter is sealedwithin the housing, would likely perform poorly under the changing waterlevels and other conditions of a pool or spa during use.

Thus, there exists a need for an inexpensive, convenient, andfunctionally efficient filter for use in spas and the like that is botheasily reusable and disposable.

SUMMARY OF THE INVENTION

The present invention is directed to an internal spa filter including afilter body and a complementary filter bag having a sheath whichencompasses the exterior of the filter body and an internal pocket whichextends into the filter body. The filter body is configured to beinstalled within a spa's water circulation system in order to filterparticles and debris out of the water. As the spa water is circulated,through the filter body a vortex effect is created within the filter bagpocket trapping debris therein for later removal without the risk of thedebris falling off the filter and back into the spa water. Theconfiguration and materials of the spa filter of the present invention,as compared to the prior art filters, provide for much higher flow ratesthrough the filter, further enhancing both the performance and life ofthe pump of the spa circulation system. Moreover, the spa filter of thepresent invention is relatively inexpensive to manufacture, whereby,after prolonged use, the filter bag itself may be either readily cleanedand reused or alternatively simply discarded.

The filter body of the spa filter of the present invention is defined bya cylinder having a spa water opening at its inlet end and a spa waterdischarge orifice at its opposite end. Throughout the filter body'scylindrical wall is formed, a pattern of auxiliary spa water inletopenings. The inlet and auxiliary openings permit the passage of thecirculated spa water from the outside of the filter body to the insidethereof. The sheath of the filter bag is joined to the pocket thereofalong a circumferential inseam. Accordingly, when the bag is placedabout the filter body, the closed end of the pocket is inserted withinthe filter body's open end while the sheath encompasses the outsidesurface of the filter body's cylindrical wall, with the inseam of thefilter bag positioned substantially along the inlet edge of thecylindrical wall's inlet end to maintain the position of the filter bagon the supporting filter body. The pocket extends towards the dischargeend of the filter body.

One embodiment of the filter body utilizes a cylinder, the sides ofwhich are formed with a pattern of round through-hole openingspreferably having a nominal diameter of 0.60″. For a cylinder having anoutside diameter of approximately 5½ and a length of approximately 8″,sixteen such holes are radially-spaced apart in each of six parallel,circumferential rows in the wall to yield a total of ninety-six throughholes generally spaced uniformly throughout the wall. In an alternativefilter body embodiment, a mesh-type pattern is formed in the cylindersidewall having a pattern of small, square apertures throughout the wallarranged in spaced-apart relationship about parallel circumferentialrows substantially throughout the wall. Because the square apertures arerelatively smaller than the through-hole apertures of the firstembodiment, for the same overall dimensions of the wall, the number ofsquare apertures and the number of rows are significantly increased,yielding a total of more than two-thousand square apertures. A thirdembodiment of the filter body of the present invention has lengthwiseaxially extending slots formed about its circumference.

In each embodiment of the filter body, the body includes an open inletend about which the filter bag sheath is draped and an opposite rearclosed discharge end formed by a rear wall integral with the rear end ofthe filter body and generally normal to the axis of the filter body. Acentral circular discharge orifice is provided in the wall for dischargeof the flow of the spa water entering the filter body through the filterbag. A length of tubing extends from the discharge orifice normal to therear wall and projecting axially away from the filter body. The tubingis configured with external threads for threadably engaging piping ofthe spa's circulation system. Preferably, the filter body will bepositioned vertically within a filer-receiving bag of the spa with theinlet end of the cylinder disposed above the discharge end thereof sothat water from the tub of the spa is drawn downwardly through thefilter body to the suction end of the spa's pump. The filter body may beconstructed of a thermoplastic material such as polyethylene (PE),polypropylene (PP), polyvinyl chloride (PVC), or acrylonitrile butadienestyrene (ABS). These materials are readily available, are relativelyinexpensive, and are easily processed using injection molding andfinishing techniques known in the art.

The filter bag of the present invention includes a support ring at thejuncture of the sheath and pocket along a circumferential inseam formedby looping the upper end of the pocket over the upper end of the sheathto form a loop or circumferential cavity. The support ring preferablyhas a nominal diameter substantially equivalent to the nominal diameterof the filter body so as to be positioned adjacent the upper end of thefilter body when the filter bag is placed on the filter body, therebymaintaining the filter bag in position and keeping the pocket openduring use. To this end, the support ring is to be constructed of anysuitable rigid or semi-rigid material such as a thermoplastic materialor stainless steel. To maintain the position of the support ring withinthe circumferential cavity and to secure the inseam, stitching, welding,stapling or other fabric attachment means known in the art are employed.

A removal handle spans the open upper end of the filter bag pocket andis attached at two opposite locations. The handle may be stitched,welded, or otherwise joined to the filter bag using any attaching meansknown in the art, but is preferably attached within the inseam itself.The length of the handle is sufficient to loosely span the pocketopening, so that the handle may droop within the pocket when not in useand may be pulled up for convenient access when the handle is to begrasped to remove the filter bag from the filter body.

The filter bag of the present invention may be constructed of a durable,porous, fibrous material known in the art for use in various filtrationapplications. Though many types of fabrics may be used in fluidfiltration to effectively remove debris and particulate matter whileallowing the fluid itself to pass through the filter media, in apreferred embodiment, the material selected will have a porosity ratingof 40 to 50 microns and have a weight on the order of 12 oz/yd².Examples of suitable materials include polypropylene (PP), polyethylene(PE), polyester felt, or fiberglass. The handle may be made of the samematerial as the sheath and the pocket or may be made of a conventionalcotton and polyester textile material.

In operation, after the sheath of the filter bag has been removablypositioned in covering relationship over the filter body with the bagpocket extending into the filter body, the internal spa filter of thepresent invention is ready for use and is installed within thefilter-receiving bay of a conventional spa with the filter in directcommunication with the spa's circulation system on the suction side ofthe pump. Once the spa tub is filled with water and the circulationsystem is operated, the water is drawn through the filter by the pump.Because the inlet opening of the filter bag, approximately 5½ diameter,is relatively larger than the discharge orifice at the closed end of thefilter body, which is typically on the order of 1½, this difference inarea will naturally create a vortex tending to draw the water downthrough the filter pocket, pulling larger debris into the pocket andtrapping it there for later removal. The vortex action and the resultingstrong suction of water through the filter also creates a vacuumpressure on the inside of the filter that serves to pull the filterbag's sheath tightly against the exterior of the filter body, thuseffectively creating a tight fit between the sheath and the filter bodywhich causes all water being pulled through the filter to pass throughthe filter bag.

The porosity of the filter bag material, the configuration of the openpocket, and the vortex effect cooperate to provide for higher flow ratesthrough the filter (on the order of about 150 gallons per minute) ascompared to conventional prior art spa filters. This increased flow ratetranslates to enhanced performance of the spa in terms of the relaxationand therapeutic benefits to the user and the life of the circulationpump.

When the filter bag of the present invention has become sufficientlydirty that it should be cleaned or replaced, the spa's circulationsystem is shut down and the filter bag is simply lifted out of thefilter body by grasping the handle. The debris trapped by the filterduring use will remain within the inside pocket, thereby notcontaminating the spa water as the filter bag is removed from thefilter-receiving bay. If the filter bag is removed from the spa to becleaned for reuse, the bag is dumped or rinsed out to remove all debristhat has been trapped or alternatively may be washed or laundered in aconventional washing machine and dryer to more thoroughly clean andsanitize the bag. If it is preferred that the filter bag be replacedrather than being cleaned, the used filter bag may be simply discardedand a new bag put into the filter body. Because the materials andconstruction methods employed in producing the filter of the presentinvention are relatively inexpensive, disposing of the filter bag isboth a convenient and economical it cleaning the bag.

Other features and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, which illustrate, by way of example, the featuresof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away perspective view of an internal spa filterembodying the present invention showing the filter bag positioned on thecylindrical filter body;

FIG. 2 is a perspective view of the filter body shown in FIG. 1;

FIG. 3 is a broken perspective view of the discharge end of the filterbody shown in FIG. 1;

FIG. 4 is a perspective view of a first alternative embodiment of thefilter body;

FIG. 5 is a perspective view of a second alternative embodiment of thefilter body;

FIG. 6 is a cut away perspective view of the filter bag shown in FIG. 1;

FIG. 7 is a cut-away perspective view of the filter bag positioned uponthe filter body of FIGS. 1, 2, and 3;

FIG. 8 is a vertical sectional view taken along line 8—8 of FIG. 7;

FIG. 9 is a perspective view of an internal spa filter of the presentinvention installed within a spa's filter-receiving bay.

FIG. 10 is a cut-away perspective view of said internal spa filterduring operation of the spa's water circulation system;

FIG. 11 is a vertical sectional view showing the operation of a vortexcreated during operation of the spa's water circulation system; and

FIG. 12 is a broken sectional view showing a filter bag being removedfrom a spa's filter-receiving bay.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As shown in the drawings for purpose of illustration, an internal spafilter of the present invention utilizes a filter bag removably disposedupon a cylindrical filter body and configured to be installed within aspa's circulation system in order to filter particles and debris out ofthe spa water. While the spa filter embodying the present invention isdescribed and depicted as being used in a conventional spa, it will beappreciated that the invention can also be used in conjunction withabove- and below-ground swimming pools, hot tubs, Jacuzzis, or with anyother system involving recirculated water that is to be filtered.

More particularly, referring to FIG. 1, a preferred embodiment of aninternal spa filter F of the present invention includes a cylindricalfilter body FB and a filter bag B having a cylindrical sheath 20 and apocket 22 that extends concentrically inwardly from the inlet end of thesheath. The upper end of the cylinder 24 of the filter body is open todefine an inlet opening 26 for spa water drawn downwardly through thecylinder by the pump 28 of the spa's water circulation system (FIG. 9).The lower end of the cylinder 24 is closed by a bottom wall 30 centrallyformed with a discharge orifice 32 (FIG. 3). The sidewalls 34 ofcylinder 24 are formed with auxiliary spa water openings in the form ofholes 36 that admit spa water that is drawn into cylinder 24 throughsheath 20 of the filter bag. In the use of the internal spa filter F allspa water being circulated through the filter will pass through and befiltered by the filter bag. Moreover, the discharge orifice 32 issmaller in area than the inlet opening 26 so that a vortex 37 is createdduring circulation of the spa water which traps debris in the pocket 22for later removal as indicated by the arrows in (FIGS. 10 and 11). Ahandle 38 is provided on the filter bag to permit the bag to beconveniently lifted from the filter body for cleaning or replacement.

A short tube 40 coaxial with the discharge opening 32 extends downwardlyaway from cylinder end wall 30 to form a water connection means betweendischarge orifice and the suction end of pump 28 (FIG. 9) of the spa'swater circulation system. The tube 40 is formed with threads 42 forthreadably engaging piping 44 connected to pump 28. A preferredconventional thread size is 1.50 mps with a major thread diameter ofapproximately 1.90″. This thread configuration accommodates a bore 64through the tubing 60, and thus a circular opening size, of about 1½″.

With continued reference to FIG. 2, the holes 66 are round andpreferably have a nominal diameter of about 0.60″. In this sameembodiment, sixteen such holes are radially-spaced apart in each of sixparallel, circumferential rows in the cylinder 24 to yield a total ofninety-six through holes generally spread uniformly throughout the wallof the cylinder sidewall. It will be appreciated that the cylinder maybe of a variety of lengths and diameters and that as the overalldimensions of the cylinder change, the pattern of holes may changeaccordingly in order to maintain a generally uniform distribution of theholes throughout the wall of the cylinder. In the embodiment shown inFIG. 2, the cylinder is configured with a nominal outside diameter of 5½and a length of 8″, as is typical in the art of spa filters, permittinga filter of the present invention to be capable of use with the majorityof spas currently on the market.

The filter body FB may be constructed from a number of differentwater-resistant materials known in the art. A preferred material is athermoplastic such as polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), or acrylonitrile butadiene styrene (ABS). It will beappreciated that these materials are readily available, are relativelyinexpensive, and are easily processed using injection molding andfinished techniques known in the art. Because the filter body isconfigured to be one integral unit, the injection molding process isboth effective and efficient in this application. In an alternativeembodiment, the threaded tubing 40 may be formed separately through amolding or machining operation and bonded or welded to the filter bodyin a secondary operation.

Referring now to FIG. 4, an alternative embodiment of filter body FB′ ofthe present invention, utilizes a cylinder 46 having a pattern ofauxiliary water openings in the form of small apertures 48 formedthroughout the wall of the cylinder to define a mesh-type construction.Preferably the apertures will be square shaped. Apertures 48 arearranged in spaced-apart relationship about parallel circumferentialrows substantially throughout the wall of cylinder 24′, but, because theapertures are relatively smaller than the through-holes 36, the numberof apertures and the number of rows are significantly increased. Thus,in one such embodiment, a cylinder 24′ having a 5½ nominal outsidediameter and an 8″ length is configured with thirty-three rows ofsixty-nine ⅛″ apertures each and, thus, has a total of 2,277 aperturesin the tubular wall. It will be appreciated that though the number ofapertures is significantly increased over the number of through-holes inthe filter body FB of FIG. 2, the total area for throughput of fluidfrom the outside of the filter body to the inside is not necessarilyincreased commensurately, but is, however, increased significantly. Forexample, in the exemplary embodiments disclosed, the total throughputarea for the ninety-six through-holes (FIG. 2) is 27.1 in² as comparedto a total throughput area for the 2,277 apertures (FIG. 3) of 35.6 in².As with the filter body FB, the mesh filter body FB′ includes a flatwall 30′ formed with a discharge orifice 32′. A central,externally-threaded tube 40′ extends from wall 30′ for engaging thespa's circulation system. The front of cylinder 24′ defines a spa waterinlet opening 26′.

With reference now to FIG. 4, there is shown a third embodiment of afilter body FB″ of the present invention. Filter body FB′ utilizes acylinder 24″ having auxiliary spa water openings in the form oflengthwise rectangular slots 52 formed about its sidewall. Slots 52 aredefined by lengthwise, radially spaced-apart ribs 54 which extend alongthe wall of the cylinder. As with both the filter body FB andaforedescribed mesh filter body FB′, the ribbed filter body FB″ includesan inlet opening 26′ and an integral bottom wall 30″. Bottom wall 30′ isformed with a central circular discharge orifice 32″ from which extendsan integral threaded tubing 56 for engaging piping 40″ of thecirculation system of a spa.

In the embodiment of the ribbed filter body FB″, shown in FIG. 5, thenominal outside diameter of the cylinder is approximately 5½″ and theoverall length is approximately 8″, just as for the aforedescribedfilter body FB and the mesh filter body FB′. Twelve lengthwise ribs 54may be spaced evenly about the circumference of the filter body atsubstantially 30-degree intervals, with each rib having a radial widthof about 0.125″. In this embodiment, the total throughput area for thetwelve slots 52 is about 110 in², a significant increase over thethroughput areas for both the filter bodies FB and FB′. The effect ofthe throughput surface areas of the various embodiments on theperformance of the internal spa filter under use is explained below.

Referring now to FIGS. 6, 7, and 8, the filter bag F of the presentinvention includes a generally tubular outside sheath 20 attached to agenerally conical inside pocket 22 along a circumferential inseam 60.The sheath has an upper inlet end 62 and a lower, discharge end 64,while the pocket has an upper end 66 continuous with the upper end ofthe sheath, and a lower end 68. The inseam 60 is formed by the union ofthe sheath and pocket along their respective upper ends. The lower end68 of the pocket is stitched, welded, or otherwise formed closed toprovide a radiused tip at the bottom of the generally conically shapedcavity 70.

Preferably in the filter bag F of the present invention, both the sheath20 and the pocket 22 are constructed of a durable, porous, fibrousmaterial known in the art for use in various filtration applications. Itwill be appreciated that many types of fabrics may be used in fluidfiltration to effectively remove debris and particulate matter whileallowing the fluid itself to freely pass through the filter media. In apreferred embodiment, the material selected will have a porosity ratingof about 40 to 50 microns. Such a material would typically have a weighton the order of 12 oz/yd². Examples of suitable materials includepolypropylene (PP), polyethylene (PE), polyester felt, or fiberglass.Polypropylene is preferred, particularly for its longevity as comparedto other similar fabrics.

The arcuate shaped handle 38 spans the open upper end 61 of the pocket22 and is attached to the filter bag 20 at the inseam 60. Opposite firstand second handle ends are attached at the inseam at approximately 180degrees apart, on opposite sides of the sheath and pocket. The handlemay be stitched, welded, or otherwise joined to the filter bag using anyattaching means known in the art. The length of the handle is to besufficient to loosely span the pocket opening, so that the handle maydroop within the pocket when not in use and may be pulled up forconvenient access when the handle is to be grasped to remove the filterbag from the filter body. The handle may be made of the same material asthe sheath and the pocket or may be made of a conventional cotton andpolyester textile material known for its durability, minimal shrinkageand wide range of uses.

Referring now to FIGS. 7 and 8, the inseam 60 is formed by looping theupper edge of the pocket over the upper end of the sheath so that theupper end of the pocket is substantially turned back on itself 180degrees to contact both the inside and outside surfaces of the uppersheath end. In a preferred embodiment, sufficient clearance is leftbetween the upper sheath end and the looped portion of the upper pocketend to form a loop or circumferential cavity 70 about the inseam 60.Disposed within the circumferential cavity is a support ring 72 of acircular cross-section. The support ring preferably has a nominaldiameter substantially equivalent to the nominal diameter of the filterbody so as to seat on the top end of the filter body when the filter bagis placed on the filter body, thereby maintaining the filter bag inposition on the filter body and keeping the upper end of the pocket openduring use. The support ring 72 is constructed of any suitable rigid orsemi-rigid material such as a thermoplastic or stainless steel. Beyondthe mechanical attributes of the support ring, the selected materialmust be water and corrosion-resistant. To maintain the position of thesupport ring 72 within the circumferential cavity 70 and to secure theinseam 60, a double-stitch 74 may be employed. As shown in FIG. 8, thestitch is to pass below the circumferential cavity through the outside,looped portion of the upper pocket end, through the upper sheath end,and then through the inside portion of the upper pocket end to hold theinseam together. It will be appreciated that the inseam may also besecured by other stitch configurations, welding, stapling or otherfabric attachment means known in the art.

Referring now to FIG. 1, in preparing an internal spa filter F of thepresent invention for use, the filter bag FB is positioned on the filterbody by sliding the lower sheath end 30 over the top end of the filterbody until the top inseam 60 is substantially aligned with the top endof the filter body. In order for the filter bag to have a loose butfunctional fit on the filter body, the inside diameter of the sheath 22is to be at least 0.100″ larger than the outside diameter of the filterbody, but no more than 0.300″ larger, which would create a clearance ofat least 0.050″ between the filter bag and the filter body about thecircumference. Thus, for example, in the embodiment of the filter bodyhaving a nominal outside diameter of 5½″, the inside diameter of thefilter bag sheath would be at least 5.600″. In order for the filter bagto be in covering relationship about the outside surface of the filterbody, the overall axial length of the sheath is preferably substantiallyequivalent to the axial length of the filter body's cylinder. In thisway, when the filter bag is advanced as far as possible along the filterbody and the inseam adjacent filter body's top end, the discharge end 64of the sheath will be substantially adjacent the filter body's bottomend.

With continued reference to FIG. 11, at the same time that the filterbag's sheath 20 is slidably advanced along the outside surface of thefilter body cylinder 24, the pocket 22 is inserted through the filterbody's inlet opening 26. The overall length of the pocket is preferablyconfigured such that when the filter bag is operationally positioned onthe filter body, the pocket's bottom end is substantially adjacent tothe discharge orifice 32. In this way, the available surface area of thefilter bag 20 for filtration is maximized without risking occlusion ofthe opening at the filter body's discharge end.

Referring now to FIG. 9, the water circulation system includes a pump 28and discharge jets 80 interconnected by piping 44 disposed in the spatub 81. A recessed, filter receiving bay 82 is formed in a wall 84 ofthe spa. After the filter bag B has been positioned in coveringrelationship over the filter body of FIG. 1, 4 or 5, the internal spafilter of the present invention is ready to be positioned within the bay82. As described above, the filter body is an externally-threaded tube40 which is connected to piping 44 upstream of the suction end of pump28 so as to dispose the filter F in communication with the spa's watercirculation system. Preferably the filter F is arranged vertically onthe floor 83 of the filter receiving bay in a water-tight fashion withrespect to such bay. Once installed, the door 86 of the filter-receivingbay is closed over the opening to the bay in order to protect users ofthe spa from inadvertent contact with the filter.

In the use of the aforedescribed internal spa filter, the first step isto fill the tub 81 with water (not shown). In the conventional spasknown in the art, the filter-receiving bay 82 and the filter F itselfare configured such that when the spa tub is filled appropriately, theentire filter is submerged, with the top of the filter typically beingat least two inches below the surface of the water. As the internal spafilter F of the present invention is configured to replace theconventional spa filters known in the art, it will be appreciated thatit, too, will be located beneath the surface of the water in the spa.Once the spa tub is filled, the pump 28 is operated so as to circulatethe water within the circulation system. The pump has an inlet (suction)side 88 and an outlet (discharge) side 90, so that the water is pumpedthrough the system in one direction as indicated by the arrow 92.

In operation, the water contained in the spa's tub 81 first passesthrough inlet windows 94 in the filter-receiving bay door 86. Thewindows are positioned in the door such that when the door is closed andthe spa is properly filled with water, the water level should fallbetween the top and bottom edges of the windows. It will be appreciatedthat in this way, larger debris that typically floats on the surface ofthe water such as leaves, twigs, hair, insects, etc., will be able tofloat through the windows and into the filter-receiving bay 82. Thewater is then drawn downwardly through the filter F by the pump 28.Because the inlet opening 26 of the filter body at its upper end, isrelatively larger than the discharge opening 32 at the closed bottom endof the filter body the filter pocket 22 as shown in FIGS. 10 and 11. Itwill be appreciated by those skilled in the art that because the waterlevel in the spa is above the top edge of the filter and the largerdebris that typically floats on the water can pass through the windowsin the filter-receiving bay door, the vortex action within the filterpulls the larger debris 96 into the pocket and traps it there for laterremoval.

The vortex action and the resulting strong suction of water through thefilter F of the present invention when the spa's circulation system isoperated also creates a negative, or vacuum, pressure on the inside ofthe filter and serves to pull the sheath 22 of the filter bag 20 tightlyagainst the exterior of the filter body. Throughput is increased throughthe various embodiments of the filter body (FIGS. 2-4), the effect ofthe sheath being pulled tightly against the outside surface of thefilter body is increased accordingly. It will be further appreciatedthat as the sheath is pulled tightly against the outside surface of thefilter body during use, effectively, a tight fit is created. Therefore,all spa water passing through the auxiliary spa water inlet openingsmust pass through the filter bag's sheath.

The design and structure of the internal spa filter of the presentinvention provides yet another benefit for both the use and life of thespa. The porosity of the filter bag B material, the configuration of thepocket 22, and the vortex effect achieved through the relativelyunimpeded swirling action of the water passing through the pocket andout of the filter body cooperate to provide for much higher flow ratesthrough the filter than can be achieved by the commonly-used prior artcartridge filters. Typically, new and clean cartridge filters arecapable of flow rates on the order of 100 gallons per minute, as limitedby the material and structure of the pleated filter media. Whereas, thefilter bag B disclosed herein is capable of flow rates of more than 150gallons per minute, for a flow rate increase of approximately 50%. Itwill be appreciated by those skilled in the art that this increased flowrate translates to increased efficiency of the spa. For example, theincreased flow rate allows for a more forceful flow of water from thespa jets 80, increasing the relaxation and therapeutic benefits to theuser. Relatedly, the increased flow rate achieved through the filter ofthe present invention improves the performance and capabilities of stateof the art jet configurations involving multiple “total body” jets or“waterfalls,” for example. Moreover, because the circulation pump 28 iseffectively working against less resistance from the filter, it does nothave to work as hard to generate the increased flow rates, therebyprolonging the life of the pump.

With continued reference to FIG. 12, when the filter bag B has becomedirty and is to be cleaned or replaced, the spa's circulation system isshut down and the door 86 to the filter-receiving bay 82 is opened. Thefilter bag 20 may then be lifted out of the filter body FB by simplygrasping the handle 38 and pulling the bag up and out of the filterbody. It will be appreciated that the debris trapped by the filterduring use will be, for the most part, contained within the filter bagpocket. In this way, when the filter bag is removed, the risk that anydebris will fall out of the pocket and back into the spa water or intothe clean side of the circulation system is reduced as compared to thetypical prior art cartridge filter, where all debris is trapped on theoutside of the filter and can easily fall off the filter and back intothe spa when the filter is removed. Moreover, because the filter bag Bis capable of being removed without unscrewing and removing thesupporting filter body, the risk of loosening trapped debris and itfalling back into the spa water is further reduced because of thedecreased handling and manipulation of the filter. Aside from bettermaintaining the cleanliness of the spa water, the spa filter of thepresent invention is also more convenient to use, because of the reducedhandling and the simplicity of lifting up on the filter bag handle toclean or replace the filter bag.

Once the filter bag B is removed from the spa, the bag may simply bedumped or rinsed out to remove all debris that has been trapped.Further, because of the structure and materials of the filter bag, thefilter bag may also be washed or laundered in a conventional washingmachine and dryer to more thoroughly clean and sanitize the bag. As isknown in the art, to further sterilize the filter bag and chemicallybreak down and remove any suntan lotions and other oils, calcificationbuild-up, and the like, the bag may be soaked in a cleaning solutionmade up of water and an active ingredient such as tri-sodium phosphateor muriatic acid. If the filter bag has been in use for many months oris otherwise showing wear or other effects of use, making cleaning andreuse of the bag less optimal, the bag may be simply discarded and a newbag put into use. It will be appreciated that the materials andconstruction methods themselves employed in producing the filter of thepresent invention are known in the art and are relatively inexpensive,causing disposability of the filter bag to be a convenient andeconomical option in the user's ongoing spa maintenance program.

While embodiments of the invention have been illustrated and described,it will be apparent that various modifications can be made withoutdeparting from the spirit and scope of the invention. Accordingly, it isnot intended that the invention be limited, except as by the appendedclaims.

What is claimed is:
 1. An internal filter for connecting water from aspa to the suction end of a spa water circulation system, said filtercomprising: a filter body that includes a cylinder having a spa waterinlet opening at one end and a spa water discharge orifice at itsopposite end, the sides of such cylinder being formed with auxiliary spawater inlet openings; a filter bag that includes a cylindrical sheathwhich extends from the rear end of the filter body encompassing theexterior of the filter body, such filter bag also being formed with apocket that extends concentrically inwardly from the front end of thesheath rearwardly into the filter body from the main spa water inletopening; and water connection means between the filter bag dischargeopening and the suction end of the spa water circulation system wherebyupon operation of the spa water circulation system spa water is drawninto the main spa water inlet opening and through the filter bag pocketinto the interior of the filter body while concurrently spa water isdrawn transversely through the filter bag sheath and auxiliary spa wateropenings into the confines of the filter body, with all of such spawater flowing rearwardly and then out of the filter body through thefilter body discharge orifice.
 2. An internal spa filter as set forth inclaim 1 which further includes a handle on the filter bag for removingthe filter bag from the confines of the filter body.
 3. An internal spafilter as set forth in claim 2 wherein the filter body discharge orificeis smaller than the filter body spa water inlet opening whereby spawater flowing through the filter body forms a vortex that traps debriswhich is too large to pass through the filter bag pocket within thepocket.
 4. An internal spa filter as set forth in claim 2 which furtherincludes a support ring which is attached to the sheath to abut the endof the filter body adjacent the spa water inlet opening of such filterbody.
 5. An internal spa filter as set forth in claim 1 wherein theauxiliary spa water inlet openings are holes.
 6. An internal spa filteras set forth in claim 1 wherein the auxiliary spa water inlet openingsare of a mesh-type construction.
 7. An internal spa filter as set forthin claim 1 wherein the auxiliary spa water inlet openings are aplurality of axially extending slots.
 8. An internal spa filter as setforth in claim 1 wherein the filter body discharge orifice is smallerthan the filter body spa water inlet opening whereby spa water flowingthrough the filter body forms a vortex that traps debris which is toolarge to pass through the filter bag pocket within the pocket.
 9. Aninternal spa filter as set forth in claim 1 which further includes asupport ring which is attached to the sheath to abut the end of thefilter body adjacent the spa water inlet opening of such filter body.10. An internal filter for connecting water from a spa to the suctionend of a spa water circulation system, said filter comprising: a filterbody that includes a vertically extending cylinder having a spa waterinlet opening at its upper end and a spa water discharge orifice at itslower end, the sides of such cylinder being formed with auxiliary spawater inlet openings; a filter bag having a cylindrical sheath whichextends upwardly from the lower end of the filter body to the upper endof such filter body, the sheath encompassing the exterior of the filterbody, such filter bag also being formed with a pocket that extendsconcentrically downwardly from the upper end of the sheath downwardlyinto the filter body from the main spa water inlet opening; and waterconnection means between the filter bag discharge orifice and thesuction end of the spa water circulation system whereby upon operationof the spa water circulation system spa water is drawn downwardly intothe main spa water inlet opening and through the filter bag pocket intothe interior of the filter body while concurrently spa water is drawntransversely through the filter bag sheath and auxiliary spa wateropenings into the confines of the filter body, with all of such spawater flowing downwardly out of the filter body through the filter bodydischarge orifice.
 11. An internal spa filter as set forth in claim 10which further includes a handle on the filter bag for removing thefilter bag from the confines of the filter body.
 12. An internal spafilter as set forth in claim 11 which further includes a support ringattached to the sheath to abut the end of the filter body adjacent thespa water inlet opening of such filter body.
 13. An internal spa filteras set forth in claim 10 wherein the auxiliary spa water inlet openingsare holes.
 14. An internal spa filter as set forth in claim 10 whereinthe auxiliary spa water inlet openings are of a mesh-type construction.15. An internal spa filter as set forth in claim 10 wherein theauxiliary spa water inlet openings are a plurality of axially extendingslots.
 16. An internal spa filter as set forth in claim 10 wherein thefilter body discharge orifice is smaller than the filter body spa waterinlet opening whereby spa water flowing through the filter body forms avortex that traps debris which is too large to pass through the filterbag pocket within the pocket.
 17. A spa construction, comprising: a tubhaving water discharge jets; a spa water circulation system thatincludes a pump; a filter-receiving bay in communication with said tub;a filter body that includes a vertically extending cylinder having a spawater inlet opening at its upper end and a spa water discharge orificeat its lower end, the sides of such cylinder being formed with auxiliaryspa water inlet openings; a filter bag having a cylindrical sheath whichextends upwardly from the lower end of the filter body to the upper endof such filter body, the sheath encompassing the exterior of the filterbody, such filter bag also being formed with a pocket that extendsconcentrically downwardly from the upper end of the sheath downwardlyinto the filter body from the main spa water inlet; and piping disposedbetween the filter body discharge opening and the suction end of thepump and between the discharge end of the pump and the tub waterdischarge jets whereby upon operation of the pump spa water is drawnfrom said tub into said bay and then downwardly into the main spa waterinlet opening and through the filter bag pocket into the interior of thefilter body while concurrently spa water is drawn transversely throughthe filter bag sheath and auxiliary spa water openings into the confinesof the filter body, with all of such spa water flowing downwardly out ofthe filter body through the filter body discharge orifice and throughthe water discharge jets back into the tub.
 18. A spa construction asset forth in claim 17 which further includes a handle on the filter bagfor removing the filter bag from the confines of the filter body and outof the filter-receiving bay.
 19. A spa construction as set forth inclaim 17 wherein the filter body discharge orifice is smaller than thefilter body spa water inlet opening whereby spa water flowing throughthe filter body forms a vortex within the pocket that traps debris whichis too large to pass through the filter bag.
 20. A spa construction asset forth in claim 17 wherein the filter bag further includes a supportring to abut the end of the filter body adjacent the spa water inletopening of the filter body.
 21. A method of filtering debris from watercontained in a spa, the spa having a spa water circulation system thatincludes a suction inlet, said method including the steps of: providinga filter body that includes a cylinder having a spa water inlet openingat one end and a spa water discharge orifice at its opposite end, thesides of such cylinder being formed with auxiliary spa water inletopenings; providing a filter bag having a cylindrical sheath thatencompasses the exterior of the filter body and a coaxial pocket thatextends into the filter body from the spa water inlet openings; andconnecting the filer body discharge orifice to the suction inlet of thespa water circulation system whereby upon operation of the spa watercirculation system water is drawn axially into the main spa water inletand through the filter bag pocket into the interior of the filter body,while concurrently water is drawn transversely through the filter bagsheath and auxiliary spa water openings into the confines of the filterbody, with all of such spa water flowing through the filter bag and thenout of the filter body through the filter body discharge orifice.
 22. Amethod as set forth in claim 21 wherein the filter body dischargeorifice is formed smaller than the filter body spa water inlet openingwhereby spa water flowing through the filter body creates a vortex thattraps debris which is too large to pass through the filter bag pocketwithin the pocket.
 23. A method as set forth in claim 21 which furtherincludes providing the filter bag with a handle and using the handle toremove the filter bag from the filter body when such filter bag is to becleaned or replaced.
 24. A method as set forth in claim 22 which furtherincludes providing the filter bag with a handle and using the handle toremove the filter bag from the filter body when such filter bag is to becleaned or replaced.